The biggest advantage of a luxury cruise, says Erica Silverstein of Cruise Critic, is that the ships are usually smaller with a higher space-to-person ratio, "so you're not fighting the crowds quite as much during scenic cruising to the glaciers."

"Anyone can enjoy a luxury cruise, but it's the people who are most concerned about spacious accommodations, top-notch service and fine dining who will truly benefit," she says.

The experience: If at-your-elbow service makes you uncomfortable, you might want to consider something else. The main strengths of the ultra-luxury ship in Alaska are the five-star-hotel service and amenities on board, along with the smaller population and the all-inclusive pricing. Off the ship, the differences tend to fade with the exception of one or two higher-end excursions, and the fact that the midsize luxury ships can stop at less frequently traveled ports, as well as ones that can't accommodate the largest ships. That means not just fewer people in line to get on or off the ship, but also small Alaskan fishing villages that don't feel overrun like Normandy on D-Day. What these ships lack in evening entertainment - some live music and performers doing show tunes - they make up for in enrichment programming: lectures, demonstrations and tours focused on learning about food, history, culture or whatever's available.

Who goes? Return cruisers, honeymooners, empty-nesters either on a splurge or just happy to spend the kids' inheritance, anyone who appreciates (and is willing to pay for) Downton Abbey-like service, an elegant setting and far fewer shipmates, as well as traditionalists who still prefer to dress for dinner.

Likely ports: One or more of the standard stops (Juneau, Skagway, Ketchikan), as well as Wrangell, Sitka, the Hubbard Glacier and Prince Rupert, B.C. A popular itinerary includes flying into Seward or Homer, eliminating one or more of the days at sea sailing from Vancouver to southeastern Alaska.

Dining: More likely to be open seating (when and where you want) with a variety of restaurants that, in general, do not cost extra. With the smaller venues and fewer passengers to serve, expect the menu and the dishes to be a step (or two) up from the mainstream lines.

Amenities/comfort: The ultra-luxury ships tend to be all-suites (depending, of course, on your definition), with room to get around easily and, possibly, entertain guests. While the fare might be two or three times the cost of a comparable mainstream cruise, some of the ultra-luxury lines wisely have chosen to eliminate the nickel-and-diming so common in the mainstream market. With Regent Seven Seas, for instance, the fare covers the cruise, cruise tours, all of the restaurants, gratuities, excursions and all soft drinks and alcohol.